I think this is my next project car

The spicer link is good information. Especially on driveshaft speed and working angles.

My nova had the big block mounts in it before the LS went in and they were offset 3/4" to the right. But that's not the problem. The center line of the engine/trans and the center line of the car is not parallel and the back of the trans is way low. Trans looks to be down about 5 deg. But I can't get very accurate with the angle finder I have, but I'm going to get a digital one and it will tell me exactly where it is. I'll probably have to buy some shims to get the angle right on the rear axle. I think the 9" was set up for a standard height car

I have one of those angle finders you get at a hardware store and it's worthless. It sticks and you have to move it a lot to get the angle to change. Might be good for building a house, but not a car.

Home depot has this for $30. https://www.homedepot.com/p/Klein-Tools-Digital-Angle-Gauge-and-Digital-Leveler-935DAG/311131769

Horrible freight has one for $40 https://www.harborfreight.com/digital-angle-gauge-63615.html

I'll go with the klein every time over HF.

Now I just have to figure out where to set the angles
 
The engine/tranny is tilted down (front to rear) about 3 degrees to create angles for the driveshaft and u-joints to work properly. The pinion, and transmission should be parallel.
 
Ok, here is where I get confused.

I believe what Aukai is saying that everything should be parallel and at a -3 deg angle on the engine/trans, and positive 3 deg on the axle which matches the "wrong " picture.

Then correct me if I'm wrong but in the '"wrong" version of the pic pdemtrem posted everything looks parallel and perfectly in line.

In the bottom pic it shows the engine/trans and axle is level with the car and only the drive shaft is angled.

So yes I'm confused.
 
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alloy said:
Ok, here is where I get confused.

I believe what Aukai is saying that everything should be parallel and at a -3 deg angle on the engine/trans, and positive 3 deg on the axle which matches the "wrong " picture.

Then correct me if I'm wrong but in the '"wrong" version of the pic pdemtrem posted everything looks parallel and perfectly in line.

In the bottom pic it shows the engine/trans and axle is level with the car and only the drive shaft is angled.

So yes I'm confused.
Click to expand...
Wrong interpretation.

In the "Wrong" graphic, everything is parallel AND COAXIAL. Coaxial is not a correct setup .

In the "Right" graphic, the crankshaft axis is parallel to the pinion shaft axis, but they are NOT COAXIAL.

In the "Right" graphic, the driveshaft drops from the transmission tail shaft (-3°?) and therefore the driveshaft intersects the pinion shaft axis at an angle (+3°?).

The point is that Spicer joints last longer accommodating small angular shaft misalignments than they do between precisely aligned shafts.

In the "Right" graphic, you see that as the rear suspension compresses the angle gets smaller. And, as the rear suspension extends the angle gets greater.

Without further research, I do not independently know what the optimum angle is or what the acceptable tolerance is or what the acceptable range is.

3° seems reasonable to me. Crawl under a couple of unmodified RWD cars with your new inclinometer and see what you find (trans pan to driveshaft).
 
It doesn't matter what angle the engine/transmission is at (within reason, of course) as long as the tailshaft/yoke is at the same angle as the pinion... and as long as there is at least a slight angle with the driveshaft. The joint has to be at an angle to 'force' the u-joint bearings to move and not take a 'set'... the bearings will last longer if they move while driving.

You may have to adjust the angle of the engine, or the angle of the axle, or both to get it set up correctly.

-Bear
 
I'm still confused. Was going to do this earlier today but went to town and ran around for awhile, then got involved taking some dog food to a family that hit some hard times.

Here is what I have with the digital angle finder. It was a royal pain to measure the engine angle. I finally went off the transmission pan sticking the magnetic gauge to it.

The app I used is here to get the overall operating angle.

spicerparts.com

Spicer Driveline Operating Angle Calculator

Measure the angles of each component in your drivetrain, then use the Spicer Driveline Operating Angle Calculator to find the operating angle of each u-joint in your drivetrain.
spicerparts.com spicerparts.com

Here is the part of the instruction about how to set slope. I think I have it right.
  • Up: Rises from front to rear of vehicle
  • Down: Descends from front to rear
Engine, -3.6 deg back of trans lower than front of engine

drive line -1.7 deg lower in the back than front

(this is where I question my settings)

axle pointing down towards front of car at -2.4 deg

car is level at .2 deg down in the front (close as I could get it.

side to side at 1.9 deg low on the drivers side

1670727829779.png

If I toggle the last slope to down this is the result.

angle2.jpg

I'm not sure what operating angle 2 is.
 
Angle 1 is between the driving member and the driveshaft. Angle 2 is between the driveshaft and driven member.

It looks like you need to tip your axle up 6 degrees. That will put it at the same angle as the transmission.

Operating angle 1 and 2 should be equal... but NOT zero. That is your desired result.

-Bear
 
It seems unreasonable to me that the pinion shaft is pointing down. I guess there are some hot rods that have the crankshaft below the pinion shaft but I never heard of the engine/trans tilting up in the rear. Are you sure of that angle orientation?

Also, I thought you intended to raise the trans tail shaft with the new crossmember, so you'll need to remeasure the angles (and adjust the pinion shaft angle) after you get the engine & transmission where you want them.
 
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